The present disclosure relates to detecting the presence, position, concentration and/or distribution of one or more components in a composite article, and to registration inspection of a composite article, using infrared radiation and infrared detectors in conjunction with the addition of inks transparent to infrared radiation.
A vast number of applications exist in which it is necessary or desirable to monitor the presence and/or position of one or more components of a composite article during manufacturing. For instance, in a largely automated process for manufacturing disposable absorbent products such as diapers and incontinence products, certain components (e.g. support layers, absorbent pads, elastic components, fastener components, etc.) must be positioned or aligned with respect to each other and/or other components in order to produce an acceptable product. Accordingly, inspection systems are commonly used to detect the positions of such components during manufacturing. If an inspection system determines that one or more components are out of position and thus do not properly register with other components, the inspection system typically outputs one or more signals indicating that certain articles should be culled and discarded, that the process should be adjusted so as to bring out-of-position components into proper position, that the process should be adjusted so that subsequent components are brought into proper registration with one another, etc.
Although highly useful for many applications, common inspection systems have certain shortcomings. For example, such systems are not well suited for determining the presence and/or positions of components underlying other components which are substantially opaque to visible and/or ultraviolet light. Additionally, such systems are not well suited to determining the presence and/or positions of components which tend to scatter visible and ultraviolet light.
Prior art inspection systems and processes are not well suited to detecting the distribution and/or concentration level (e.g., quantity) of certain product components. Certain substances including colorants added to increasingly complex and garment-like articles have the effect of inadvertently and unintentionally acting as infrared blockers, potentially disrupting the expected performance of the kinds of inspection systems described herein.